Azurite mine removal action overview
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AZURITE MINE REMOVAL ACTION OVERVIEW. Dustin G. Wasley, PE, Principal – CES 2013 American Society of Mining and Reclamation Conference Laramie, Wyoming -- June 6, 2012. Azurite Mine Overview. Abandoned Underground Gold Mine, Located in North-Central WA on USFS-Administered Land

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AZURITE MINE REMOVAL ACTION OVERVIEW

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Azurite mine removal action overview

AZURITE MINEREMOVAL ACTION OVERVIEW

Dustin G. Wasley, PE, Principal – CES

2013 American Society of Mining and Reclamation Conference

Laramie, Wyoming -- June 6, 2012


Azurite mine overview

Azurite Mine Overview

  • Abandoned Underground Gold Mine, Located in North-Central WA on USFS-Administered Land

  • Northwest of Mazama, Near Harts Pass Recreation Area & Pacific Crest Trail

  • Remote with Poor Access, Steep Terrain

  • Several RTE Species – Aquatic and Terrestrial

  • Inventoried Roadless/Non-Motorized Management Area

  • High Value for Potential Wilderness Area in Future


Azurite mine location

Azurite Mine Location

AZURITE MINE

MAZAMA


Azurite mine removal action overview

OVERVIEW OF AZURITE MINE FROM TINSON ADIT

TAILINGS

~55,000 CY

~4 acres

CADY PASS

MILL AREA

WASTE ROCK

~22,000 CY

~1 acre

WENATCHEE ADIT

MILL CREEK

OFFICE BUILDING


Azurite mine early history

Azurite Mine – Early History

  • 1915 – 31 Claims Staked

  • 1916 – Azurite Copper Company (renamed Azurite Gold)

  • 1918 to 1931 – Underground Development

  • 1934 – ASARCO Leased Mine

  • 1934 to 1936 – 100 TPD Mill and Infrastructure

  • 1936 to 1942 –Development, Production

    • ~73,000 tons @ 0.38 opt gold

  • 1942 – ASARCO Removes Equipment


Historic photos 1936

Historic Photos - 1936


Azurite mine recent history

Azurite Mine – Recent History

  • 1995 – Discovery Assessment (USFS)

  • 2002 – IAM Open File Report (WA DNR)

  • 2004/2005 – CERCLA Site Inspection (USFS/CES)

  • 2005 – Reprocessing Study (USFS/CES); – PRP Report (USFS)

  • 2006 to 2008 – EE/CA & Risk Assessment (ASARCO/MFG)

  • 2008 – ASARCO Settlement with USFS~$5.5M

  • 2007 to 2010 – Data Gaps/Removal Design (USFS/CES)

  • 2011 – Removal Action Activities


Final removal action alternative

Final Removal Action Alternative

  • Access Road Improvements / Bridge Replacement (2010)

  • Temporary Access Road Across Mill Creek (2011)

  • Mill Creek Diversion Away from Waste Rock Pile (2011)

  • Onsite Covered Repository (2011)

    • Reinforced Stabilized Slope/Repository Toe Berm

    • Waste Rock and Mill Area Soil Blended with Tailings

    • Multi-Layer Cover, HDPE Membrane, and Talus/Rock Cover

  • Physical Hazard Closures (2011)

  • Revegetation (2011) – USFS Lead


Construction challenges

Construction Challenges

  • Weather Conditions (rain, snow, heat)


Construction challenges1

Construction Challenges

  • Weather Conditions (rain, snow, heat)

  • Typical Construction Window (late June – early October)

  • Steep Slopes / Difficult Terrain

  • Limited Onsite Staging Areas

  • All Borrow Material from Onsite

  • Remote Access/Logistics/Communication


2011 removal action summary

2011 Removal Action Summary

  • Turnkey “Design/Build” Contract Structure

    • CES – Prime Contractor

    • Palm Construction – Main Subcontractor (Local)

  • Mobilization – July 11, 2011 – 3 weeks late (weather)

  • Continuous Work Schedule, CES and Subs

  • Demobilization – September 26, 2011 – 1 week early


Azurite mine removal action overview

OVERVIEW OF AZURITE MINE REMOVAL ACTION

TAILINGS PILE

Contour with WR/Mill Soils, and Construct Repository

STABILIZED SLOPE

Construct to retain Repository

WASTE ROCK

Excavate and Haul to Repository

MILL AREA

Excavate and Haul to Repository


Camp equipment and manpower

Camp, Equipment and Manpower

  • Remote Camp (internet, phones, running water, flushing toilets, showers, washer/dryer, cook, tents/campers)

  • 3 Excavators

  • 2 Loaders

  • 3 Dozers

  • 2 Off-Road, Articulated Haul Trucks

  • Roller Compactor, Water Truck, Misc. Work Trucks

  • Bear Proof Storage Containers

  • Manpower – 10 to 20 (Palm/Subs) / 1 to 3 (CES)


Erosion and sediment control

Erosion and Sediment Control

  • Run-On Ditches

    • Waste Rock / Tailings

  • Silt Fence

    • Borrow Area / Waste Rock

  • Filter Berms

    • Borrow Area / Waste Rock

  • Sedimentation Pond

    • Tailings / Repository


Mill creek crossing and diversion

Mill Creek Crossing and Diversion

  • Access Waste Rock Pile, and Transport to Repository

  • Three, 48-inch CMPs

  • Temporarily Divert Mill Creek Away From Waste Rock Pile


Mill creek crossing

Mill Creek Crossing


Borrow area development

Borrow Area Development

  • Onsite Source for Screening / 3 Products

  • 2-inch minus

    • Stabilized Slope Fill, Road Bed/Base, Fill Material

    • 40,000+ cubic yards used, more remains onsite

  • 2-inch to 36-inch

    • Repository cover, rocked diversion ditches

    • ~20,000 cubic yards

  • 36-inch plus

    • Misc. Placement, armoring


Borrow area development1

Borrow Area Development


Borrow area development2

Borrow Area Development


Underground working closures

Underground Working Closures

  • Planned for 5 Closures (4 Adits / 1 Vent)

  • Pre-Cut Steel and Culverts Delivered to Site

  • Final Onsite Fabrication

  • Installation with Helicopter and Onsite Welder

  • 4 Closures

    • Burnham, Tinson, and Discovery Adits

    • Discovery Vent

  • Wenatchee Adit

    • Collapsed - No Bat Gate Installed


Reinforced stabilized slope

Reinforced Stabilized Slope

  • Designed to Stabilize/Retain the Repository

  • Original Design was 15-feet (H) x 15-feet (W) – 12 lifts

  • Final Layout was 22-feet (H) x 25-feet (W) – 17 lifts

    • Competent Soil Deeper Than Planned

    • Increased Quantities For Borrow Material/Geogrid

  • Onsite QA/QC Testing – All Final Tests Met Compaction Requirements (95% of Proctor)

  • 23 days to build

    • Bottom lifts ~ 1.5 days to complete

    • Upper lifts ~ 1 day to complete


Reinforced stabilized slope typical

Reinforced Stabilized Slope Typical


Reinforced stabilized slope lift 1

Reinforced Stabilized Slope – Lift 1


Reinforced stabilized slope lift 4

Reinforced Stabilized Slope – Lift 4


Reinforced stabilized slope lift 8

Reinforced Stabilized Slope – Lift 8


Reinforced stabilized slope lift 12

Reinforced Stabilized Slope – Lift 12


Reinforced stabilized slope lifts 14 15

Reinforced Stabilized Slope – Lifts 14/15


Reinforced stabilized slope complete

Reinforced Stabilized Slope – Complete


Waste rock excavation and placement

Waste Rock Excavation and Placement

  • Design Estimate was 22,000 bcy of Waste Rock

  • Risk Assessment Cleanup Goal – 104 mg/kg Total Arsenic

  • Revised Cleanup Goal – 204 mg/kg Total Arsenic

    • Additional Background Soil Sampling

    • Used MTCA Stat 3.0 to Calculate Natural Background

  • In-Field Screening with Niton XRF (RPDs ≤ 33%)

  • Final Quantities ~ 16,500 bcy


Waste rock pile before

Waste Rock Pile – Before


Waste rock pile removal

Waste Rock Pile – Removal


Waste rock pile removal1

Waste Rock Pile – Removal


Waste rock pile final

Waste Rock Pile – Final


Onsite repository

Onsite Repository

  • Overall Slope = 2.5:1

  • Reinforced Slope and Berm to Stabilize Repository

  • Waste Rock Blended with Tailings to Achieve Slope

  • In-sloped Benches Every 9 Vertical Feet

  • Repository Cover (Multi-Layer)

    • Talus/Rock Cover – Top

    • Geogrid

    • 12-oz Nonwoven Geotextile

    • 40-mil HDPE Membrane

    • 12-oz Nonwoven Geotextile

    • Waste Rock/Tailings – Bottom


Repository grading plan

Repository Grading Plan


Repository cross section detail

Repository Cross Section Detail


Tailings pile before

Tailings Pile - Before


Tailings pile before1

Tailings Pile - Before


Tailings pile oxidation profile

Tailings Pile – Oxidation Profile


Repository benching grading

Repository Benching / Grading


Repository benching grading1

Repository Benching / Grading


Repository benching grading2

Repository Benching / Grading


Liner installation

Liner Installation


Liner layers

Liner Layers


Liner installation1

Liner Installation


Liner installation2

Liner Installation


Liner cover installation

Liner / Cover Installation


Repository final

Repository – Final


Repository final1

Repository – Final


Repository tailings pile before

Repository / Tailings Pile – Before


Repository final2

Repository – Final


Summary

Summary

  • Completed 4 Weeks Ahead of Schedule

  • Field Changes Easily Made with Continuous Oversight & Communication

  • No Health/Safety Concerns

  • 3-Years of Long-term O&M Inspections, & Monitoring

  • RA Cost - $2.5M Capital


Questions

QUESTIONS


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